GMAT Tip: The Top 5 Strategies for GMAT Critical Reasoning (Part 2)

Here is the second part of the Critical Reasoning tip from Manhattan Review UK, a provider of GMAT tutoring in London. In this post, they reveal Manhattan Review’s best 5 strategies how to tackle GMAT Critical Reasoning questions. If you have missed the first part of this post, you can find it here.

Let’s continue with our strategies for GMAT Critical Reasoning with the remaining two strategies and a comprehensive example:

4. Find the flaw in the assumption

In Weaken arguments the conclusions are not warranted because the assumptions are flawed. There are many examples of flawed assumptions. Here are just a few of them:

a) Confusion of correlation with causation. If one event always takes place alongside another event, then one event is taken to be the cause of the other. Here’s an example: “Everywhere in the world a dramatic rise in ice cream consumption always goes together with an equally dramatic rise in drowning accidents. Therefore, ice cream is the cause of drowning accidents.”

The flaw in the argument is obvious: During summer months ice cream consumption rises—for obvious reasons. Coincidentally, more people are going into the water—again for obvious reasons. The more that people go into the water, the more likely it is that there will be drowning accidents. Ice cream consumption and drowning are two events that always go together but one is not the cause of the other.

b) Using an unrepresentative sample. Here’s an example:

“Research shows that students who study little often receive higher scores in their finals than students who students who studied hard. Therefore, studying is not a prerequisite for getting a good score.”

Again, the flaw isn’t hard to spot. There are unquestionably highly gifted students who do not need to study hard to do well in finals. These students, however, are highly unrepresentative of the student body. For most people, hard work is the prerequisite of a good score.

c) The fallacy of affirming the consequent. Here’s an example: “Whenever I get the flu, I always get a sore throat. I woke up this morning with a terrible sore throat. I concluded that I had the flu.”

Where’s the fallacy here? Obviously, it lies in the assumption that because the flu always causes a sore throat, no other cause of a sore throat is possible than the flu. If flu is always the cause of a sore throat, then it must be the only cause. But of course we know that a sore throat can be caused by many different maladies.

d) The fallacy of denying the antecedent. Here’s an example: “If I were a personal injury lawyer, I would be a very rich man. Sadly, I am not a personal injury lawyer. That is why I am not a very rich man.”

The fallacy here is the assumption that because becoming a personal injury lawyer is one way of becoming very rich, then it is the only way of doing so.

There are of course many other types of flawed assumptions. The point is that once you’ve identified the flaw, you can figure out what you are looking for before you peruse the answer choices. You will be looking for the statement that, if true, would bring to light the fallacy of the argument’s assumption.

5. Rehearse in your head a possible answer

Once you’ve spotted the flawed assumption, the task ahead is pretty straightforward. Nonetheless, make life as easy as possible for yourself. Rather than wade through long, sometimes convoluted answer choices, rehearse in your own mind what kind of an answer choice you will be looking for.

The computer-insomnia argument above confused correlation with causation. The correct answer would therefore have to be a statement suggesting that something other than computers could have been the cause of the insomnia. The drug-outlawing argument above relies on the assumption that other than tourism or smuggling across the border there is no way to get drug X into Andovia. The correct answer choice would therefore have to be a statement suggesting that the drug can easily be manufactured or grown locally.

Let us apply the five tips to an example, yet another one taken from the Manhattan Review Study Companion:

In a certain socialist country, party members earn twice as much as non-party members do. But party members happen to work in the businesses that generally have higher wages. Non-party members who also work in these particular businesses earn about as much as party members. Therefore, higher incomes do not necessarily result from the connection with the party.

Which of the following, if true, most seriously weakens the argument above?

(A.) Besides wage increases, party members also receive other benefits.
(B.) Some of the most highly paid business people in that country are capitalist executives in special economic zones and are not party members.
(C.) Wages in many industries vary from one part of the country to another, whether or not workers are in the party.
(D.) Non-party members in a given industry often receive higher wage as a result of the lobbying done by party members, which in turn increases the wage for the entire industry.
(E.) Becoming a member of the party within a given industry or business often encourages others to follow suit.

The wording of the question makes it clear that this is an Assumption/Weaken problem. Therefore, we need to look for the conclusion. It’s to be found in the last sentence: In this socialist country, it is not necessarily connection to the party that accounts for the higher incomes of party members.

What is the assumption here? To find it, we will need to identify the evidentiary basis of that conclusion. It is to be found in the statement that party members happen to work in businesses that pay well. Non-party members who work there, we are told, are also paid well, in fact as well as party members. The assumption therefore is that the only factor determining how much anyone earns is the pay rate in the business in which he or she is employed. Nothing else is going on. Once again, correlation is mistaken for causation.

What kind of answer choice will we be looking for? We are trying to undermine the argument that connection to the party doesn’t determine how much party members earn. Therefore, we need an answer that will suggest that businesses that pay well do so because of their connection to the party, that these businesses put a high premium on hiring party members.

Armed with this hypothetical answer, it becomes very easy to eliminate wrong answer choices. (A) fails to address the issue. It just tells us that party members enjoy benefits in addition to good pay. (B) tells us nothing that we don’t already know. Non-party members make good money too. (C) fails to explain anything. (D) is very much on the right lines. Businesses that pay well do so only as a “result of the lobbying done by party members, which in turn increases the wage for the entire industry.” That’s exactly the kind of answer we were looking for. Just because high-paying businesses in which party members work pay others well it doesn’t warrant the conclusion that party membership doesn’t determine pay rates. Party connections may have determined the pay rates in those high-paying businesses. (E) also fails to explain the correlation between party membership and pay rates.

Therefore, the correct answer is (D).

Best of luck on your GMAT! If you want to know more about the GMAT Preparation options from Manhattan Review, please attend a free interactive GMAT webinar that will feature many suggestions and tricks how to prepare for the test.

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